Preheat the oven to 160c.
Add everything, except for the tarragon and yoghurt, to a 26cm round saute pan, along with 1 teaspoon of salt and 100ml of the bean stock. Gently mix to combine, cover, and place in the oven for 1 ½ hours, stirring half way through. Remove from the oven and set aside to rest for 10 minutes. Stir in the tarragon just before serving. Serve with a dollop of yoghurt alongside.